1. Field of the Invention
This invention relates to a set of golf clubs each designed to suit a particular swing, and more particularly to a set of golf clubs each having a fiber reinforced plastic shaft incorporating helically wound reinforcing filaments over the entire length thereof, with different shaft flex characteristics most suited to a particular shaft length.
2. Prior Art
In recent years, golf club shafts formed of fiber reinforced plastic (FRP) have increasingly replaced metallic shafts to realize weight reduction. Such FRP shafts are manufactured for example by the so-called filament winding method in which reinforcing filaments, such as glass filaments and carbon filaments, are helically wound around the shaft axis.
In most of the conventional FRP club shafts, a filament winding angle (the angle formed by the helically wound reinforcing filament and the shaft axis) is constant throughout the entire shaft length, thus failing to provide a particular flex section that is most easily bendable than any other section of the shaft.
On the other hand, in Japanese Patent Publication No. 52-26794 published July 15, 1977 (Application No. 49-29078, filed Mar. 15, 1974, Inventors: Inoue et al. ) there is proposed a particular FRP club shaft incorporating helically wound carbon filaments the winding angles of which are gradually reduced as the shaft diameter varies. However, this particular prior art does not aim to provide a flex section at a specific region within each shaft length, so that mechanical or physical properties of the club shaft gradually vary continuously axially of the shaft, which is the natural consequence of the winding variation mode.
Generally, golf clubs of smaller number having longer shafts are required to have a shaft flex point (kick point) at a location closer to the club head to ensure a greater flying distance of the hit ball, whereas golf clubs of greater number having shorter shafts are required to have a shaft flex point (kick point) at a location closer to the grip to ensure controlled swing for exact drop point of ball. However, a conventional set of golf clubs of the FRP shaft type all have similar shaft flex characteristics and hence constant kick points, consequently failing to meet the above described requirements.
It is, therefore, an object of the present invention to provide a set of FRP shaft golf clubs of different length in which each club shaft has a well defined flex section and in which all shafts are individually adjusted in kick point depending on the respective length of the shafts.
According to the present invention, there is provided a set of golf clubs each having a fiber reinforced plastic shaft incorporating helically wound reinforcing filaments over the entire length thereof, the shaft comprising an intermediate flex section interposed between a head-side section and a grip-side section, a filament winding angle in the flex section being discontinuously larger than that in the head-side and grip-side sections so that a maximum bendability is provided at the flex section, wherein location of the flex section gradually differs from club to club in the set in order of club number in the manner that any club having a smaller number in the set has its flex section closer to its club head than any club of greater number in the set.
Other objects, features and advantages of the present invention will become apparent from the following detailed description.